Latex accelerator composition

Abstract

Accelerator composition for a rubber latex derived from a conjugated diene and optionally a vinyl aromatic comonomer including: (i) a diisopropyl xanthogen polysulphide (DIXP), (ii) an alkyldithiocarbamate wherein the alkyl chain contains from 5 to 20 carbon atoms, and (iii) diphenylguanidine (DPG), a curable aqueous synthetic rubber latex composition including said accelerator composition, a process for the water-based solvent-free manufacture of synthetic shaped synthetic elastomeric articles, prepared by using the accelerator composition.

What is claimed is: 
     
       1. An accelerator composition comprising:
 (i) a curable aqueous synthetic rubber latex derived from the group consisting of a conjugated diene monomer; and a conjugated diene monomer with a vinyl aromatic comonomer; while further comprising: 
 (ii) a diisopropyl xanthogen polysulphide (DIXP); 
 (iii) an alkyldithiocarbamate, wherein the alkyl chain contains from 5 to 20 carbon atoms; and 
 (iv) diphenylguanidine (DPG);
 wherein the composition is essentially free of zinc diethyldithiocarbamate (ZDEC) and zinc-2-mercaptobenzothiozole (ZMBT). 
 
 
     
     
       2. The accelerator composition of  claim 1 , wherein as component (ii) diisonyl dithiocarbamate (ZDNC) is used. 
     
     
       3. The curable aqueous synthetic rubber latex composition of  claim 1  additionally comprising:
 (v) a vulcanizing agent; and 
 (vi) an activator. 
 
     
     
       4. The curable aqueous synthetic rubber latex composition of  claim 3 , wherein the rubber latex is a poly(isoprene) rubber latex. 
     
     
       5. The curable aqueous synthetic rubber latex composition of  claim 3 , wherein each of the ingredients (i), (ii) and (iii) of the accelerator composition are present in a concentration of from 0.25 to 1.00 phr, relative to the weight of synthetic rubber solid. 
     
     
       6. The curable aqueous synthetic rubber latex composition of  claim 5 , wherein each of the ingredients (i), (ii) and (iii) of the accelerator composition are present in a concentration of from 0.25 to 0.80 phr, relative to the weight of the synthetic rubber solid. 
     
     
       7. A process for the water-based manufacture of synthetic elastomeric articles, comprising: (i) the preparation of a latex dispersion or emulsion that comprises a vulcanising agent, an activator and the accelerator composition of  claim 1 ; (ii) maturation of the latex dispersion for a period of from 0.5 to 1.5 days; (iii) dipping a former in the shape of the article into the latex; and (iv) curing the latex present on the former. 
     
     
       8. Shaped synthetic elastomeric articles, prepared from the curable aqueous synthetic rubber latex composition of  claim 3 . 
     
     
       9. Cured shaped synthetic elastomeric articles according to  claim 8 , characterized by a tensile strength of at least 24 MPa (according to ASTM D-412) and an elongation at break of at least 750%. 
     
     
       10. Shaped synthetic elastomeric articles, prepared from the curable aqueous synthetic rubber latex composition of  claim 4 . 
     
     
       11. Cured shaped synthetic elastomeric articles according to  claim 10 , characterized by a tensile strength of at least 24 MPa (according to ASTM D-412) and an elongation at break of at least 750%. 
     
     
       12. Shaped synthetic elastomeric articles, prepared from the curable aqueous synthetic rubber latex composition of  claim 5 . 
     
     
       13. Cured shaped synthetic elastomeric articles according to  claim 12 , characterized by a tensile strength of at least 24 MPa (according to ASTM D-412) and an elongation at break of at least 750%. 
     
     
       14. Shaped synthetic elastomeric articles, prepared from the curable aqueous synthetic rubber latex composition of  claim 6 . 
     
     
       15. Cured shaped synthetic elastomeric articles according to  claim 14 , characterized by a tensile strength of at least 24 MPa (according to ASTM D-412) and an elongation at break of at least 750%. 
     
     
       16. Shaped synthetic elastomeric articles, prepared from the curable aqueous synthetic rubber latex composition of  claim 7 . 
     
     
       17. Cured shaped synthetic elastomeric articles according to  claim 16 , characterized by a tensile strength of at least 24 MPa (according to ASTM D-412) and an elongation at break of at least 750%.